ARTICLE REPRINT Blending for Italian Espresso
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ARTICLE REPRINT
Blending
for
Italian
Espresso
Part 1
Background
This article and A
was originally Rationale for
published in the Blending
Jan/Feb 2008
issue of Roast
by Dr. Joseph John
Photos by James Hoffmann
EACH COFFEE-PRODUCING country a technically acceptable blend for brewed coffee,
cultivates a product that is somewhat different not every one of those blends can become a
from that of another origin. Some display high commercial success, because of taste preferences.
acidity, some have high body, others are very However, espresso in general, and Italian
aromatic, and still others taste of fruits, spices, espresso in particular, is defined much more
chocolate and even tobacco. In each case, the narrowly in terms of what physical and flavor
coffee exhibits a flavor profile in the cup that is characteristics it can exhibit. As a result, blending
characteristic of its origin—the place where the for espresso is quite different from blending for
coffee is grown. brewed coffee, because the two beverages are
Blending coffee is both an art and a vastly different.
science. In its noblest form, blending attempts Espresso blends are not created by taking
to create a cup that does not exist in nature, brewed coffee blends and roasting them darker
by mixing two or more coffees in various and more oily; such dark roasting does not
proportions. When expertly done, the resulting magically make it an espresso blend. However,
blend displays a flavor profile that is distinctly before discussing blending for espresso, the
different from those of any of the component important distinctions between ordinary brewed
coffees—often superior, sometimes more coffee and real espresso must be appreciated.
complete and, at other times, better balanced. Although this article covers the subject of
Blending for brewed coffee is relatively blending for espresso, it is not intended to
simple and straightforward, because brewed provide specific recipes for espresso blends; rather
coffee can accommodate a wide array of it is to elaborate on one blending philosophy and
physical and flavor properties. Although every to develop a practical approach to blending for an
such combination of two or more coffees in a Italian espresso.
wide range of relative proportions can constitute
continued on next page
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Due to its length and the complexity molecules released
of its content, this article is split into two by the ground coffee
parts. The first part, contained in this issue, during the extraction
develops the background information process simply escape
leading to the specific requirements of an into the room and are
espresso blend. The second part, to appear lost. Only a minute
in the next issue, will elaborate on an fraction of this aroma
approach to blending for Italian espresso. stays dissolved in the
liquid coffee.
The sweet,
Ordinary Coffee and How It Is flavorful and
Made desirable components
of ground coffee are
extremely soluble
Ordinary brewed coffee is prepared by in water and most
bringing hot water into physical contact of them are easily
with ground coffee at room pressure. In this extracted in a short
process, some portion of the ground coffee, time or by little water
roughly twenty percent by weight, dissolves flowing through
in the hot water. This is primarily a physical the ground coffee.
process. Most of the chemical reactions Longer contact Cooling in the tray.
occur after the coffee is brewed and allowed time, or more water
to linger, often resulting in deterioration of flowing through the
its fresh brewed flavors. espresso six times as strong as brewed coffee.
ground coffee, results in dissolving more of
There are many different ways of The process described so far will result in
the undesirable components such as acids,
making coffee, but they all follow the same producing only strong coffee, even if an
bitters and caffeine.
basic principle of bringing hot water and espresso machine is used, unless steps are
ground coffee into physical contact with taken to insure that oils in the ground coffee
each other. Some use steam and others What Exactly Is Espresso? are also emulsified.
If the coffee is not ground fine enough,
use a hand piston to push water through
the ground coffee, while most common the pressurized water will rush through
Espresso can only be made using a
techniques simply call for pouring the the ground coffee in less than 15 seconds
machine that not only heats the water and
hot water on top of the ground coffee or extracting only the solubles and making
pre-measures the water volume, but also
dumping the ground coffee into a vessel strong, ordinary coffee. But when the coffee
delivers the hot water under high pressure,
containing the hot water. It takes about is ground very fine and packed very tight in
ranging from 100 to 140 lbs. per square
seven grams of ground coffee to make a six- the porta-filter so as to impede the flow of
inch. This high water pressure causes the
ounce cup of coffee. Different methods of water, water molecules will be forced into
oils in ground coffee to be extracted, formed
making coffee take varying amounts of time; the interior of the ground coffee particles
into microscopic droplets and suspended
and the contact time, during which ground and made to drive out the oils, with the
in liquid coffee concentrate. It is this
coffee is in physical contact with hot water, water losing most of its energy in the
emulsification of oils that distinguishes
determines the fineness to which coffee process. The resulting espresso will simply
espresso from strong coffee.
is ground. Longer contact times call for ooze out of the porta-filter like warm honey
As in the case of brewed coffee, it takes
coarser grind, in order to control extraction. without having enough energy to gush out.
about seven grams of ground coffee to make
Because the preparation is carried out These oils completely change all the
a one-ounce, single shot of espresso. In this
at ordinary pressures, the water-soluble physical and flavor characteristics of this
process, the water-soluble components of
components of ground coffee are primarily coffee beverage. Its mouth feel, density,
ground coffee, roughly the same 20 percent
extracted and account for the taste and viscosity, wetting power and foam-forming
by weight, goes into solution, just as in the
color of the brew. The process extracts some ability are all different from those of strong
case of brewed coffee. But this is dissolved
of the water-insoluble compounds that coffee.
in only one ounce of water, making the
account for the body. Much of the aroma
continued on next page
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Significance of Crema
The emulsified oils also change the flavor properties of the
beverage. For example, these oils coat the taste buds and inhibit
their ability to detect bitterness. This reduced bitterness will be
interpreted as enhanced sweetness. Thus, if brewed coffee and
espresso are made from exactly the same blend, the resulting
espresso will actually taste sweeter.
Much of the enjoyment of consuming coffee comes from its
flavor, consisting of taste and aroma, with a majority of the flavor
sensation actually being derived from the aroma, as detected by
the nose. While much of the aroma molecules escape into the
room when brewed coffee is prepared, espresso preparation has
a built-in mechanism to capture the aroma and keep it in the
cup—the all important crema.
The emulsified oils responsible for the crema, which is a
collection of tiny bubbles with a film of oil on the outside and
the coffee’s aroma inside, provide this mechanism to hold the
aroma of fresh ground coffee in the cup. These aroma molecules,
later released when the bubbles burst in the back of one’s mouth,
find their way to the nose through the pharynx that connects
the mouth to the nasal cavity. These tiny bubbles also attach
themselves to the taste buds and burst, from time to time, to
release the volatile compounds long after the espresso is gone,
accounting for the long after-taste, a distinguishing feature of
An example of excellent crema.
espresso quality. Crema, therefore, is the single most important
indicator of a well-made espresso.
A Few Words About Acidity
Because espresso is six times stronger than brewed coffee, all
characteristics of the coffees are exaggerated in an espresso.
This is particularly true of its acidity. As the concentration of
the beverage increases linearly, the acidity perceived by the
tongue seems to increase much faster. As a result, high acidity,
considered by many to be a virtue in brewed coffee, is not a
desirable feature in a quality espresso.
This acidity has a major impact on the selection of
component coffees for an espresso blend. Much of the coffees
available in the United States and Canada are grown in Central
and South America, many of which exhibit high acidity in the
cup. Many brewed coffee blends offered in North America
showcase these Central and South American coffees both for
their flavors and their acidity. Because espresso does not tolerate
Real Espresso should ooze out of the porta filter like
thick, warm, honey. continued on next page
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ARTICLE REPRINT (CONTINUED)
anywhere near the acidity desired in brewed coffees, the role of
these high-acid coffees in espresso blends has to be curtailed.
Single-Origin Espresso
There are some, particularly in North America, who consider
espresso as just another way of making coffee. In that context,
using a single-origin coffee to make espresso may be a rewarding
experience. The espresso process magnifies all the good (and the
bad) characteristics of that coffee, and when their good features
far outweigh the negatives, this may be a way to enjoy one’s
favorite coffee. The single-origin espresso is favored by the home
connoisseur as a way to add variety to their everyday espresso
routine.
However, in a commercial environment, the single-origin
espresso is best used as a “guest espresso,” in addition to the house
espresso staple. An additional grinder for the guest espresso is a
must. This situation may change as the general quality of espresso
in North America improves and the consuming public gets more
conversant with espresso to the point that more than five percent Everything coming out of the portafilter should be
of espresso beverages are consumed as “straight”. crema.
In a caf
café or espresso bar, customers are looking for the
espressos and espresso-based milk drinks to taste exactly the that situation, espresso blend stability as well as shot-to-shot
way they tasted the last time. In such commercial environments, consistency is of paramount importance. In that context, it is
the caf
café is in the business of fulfilling peoples’ expectations. In inconceivable that one single-origin espresso can fulfill that
consistency objective if that is the only espresso offered in a caf
café.
Roast Before Blending vs.
Blend Before Roasting
As to whether it is better to roast the individual coffees separately
before blending or to blend the coffees in the green and roast them
all together depends on the properties of the coffees used in the
blend. Both procedures are completely acceptable.
Post-roast blending, where the individual coffees are roasted
separately and blended afterwards, affords the luxury of being
able to roast each coffee to a different degree to bring out the best
flavors in that particular bean. It also offers coffee retailers who do
not roast their own coffees the ability to create proprietary espresso
blends out of the individual roasted coffees they get from one or
more wholesale roasters.
However, this post-roast blending procedure has
disadvantages, the most obvious being the need to do several
batches of roasting in order to produce a blend. Also, most roasting
Initial pour must have the correct reddish-brown tinge. machines have practical minima for the quantity of coffee that can
continued on next page
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be roasted in them, and it is inevitable that
one has to roast more coffee than is required
Gold, Josuma’s premium European
espresso. The coffees used in this blend
Thus Far
for a particular blending session. If one’s cannot be more dis-similar. The Monsooned
commitment to freshness prohibits holding Malabar-AA Super Grade is extra large, We have established the difference between
coffee from today’s roasts for tomorrow’s having grown to twice the original size brewed coffee and real espresso and laid
blending, it can lead to considerable waste during the monsooning process. It is also the foundation to discuss how blending for
of the leftover component coffees. extremely low in density. The premium espresso differs from blending for brewed
Blending the green beans before roasting washed robusta Kaapi Royale, on the other coffee. In the second part we will cover a
is conceptually ideal in overcoming some of hand, is small and dense. Those beans just particular approach to blending for Italian
the disadvantages of the post-roast blending. did not want to roast together and initial espresso.
Pre-roast blending is possible when the attempts at roasting them together produced
coffee beans are compatible with respect disastrous results. It took me three years to
to their roast characteristics. When the perfect the blending procedures to enable
DR. JOSEPH JOHN is president of Josuma
beans are dissimilar in bean size, density, the blend to be roasted properly. In that
Coffee Company, in Menlo Park, Calif.
moisture content, heat conductivity and process, I learned a lot about the properties
and designer of Malabar Gold, its premium
roast development profile, blending before of those coffees and got a real education
European espresso blend. He can be contacted
roasting is difficult, and in many cases, about the mechanics of roasting.
by phone at 650.366.5453 or by e-mail at
impossible.
info@josuma.com.
Such is the case with the blend I have
the most experience with: viz., Malabar
Some Statistical Considerations
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S o m e St a tistical Considerations
WHEN AN ESPRESSO BLEND consists of two or more coffees, proportions of the beans when a single, double or triple shot is
the exact proportion of each bean in a dose will vary from shot made. They are calculated as a set of probabilities that a particular
to shot. The extent to which these proportions vary, from dose to coffee is within +/- x percent of the nominal proportion, where
dose, depends on the dose size and the relative proportion of a “x” is the heading on top of each column. For example, reading
particular bean in that blend. down the +/- 20 percent column, the numbers indicate the
It takes about 56 beans to make up seven grams of coffee, often probability that the particular sample chosen has a specific coffee
used to make a single shot of espresso. Thus, in making espresso, within +/- 20 percent of its nominal proportion.
one is conducting a random sampling experiment, selecting Suppose a blend uses 40 percent of a Sumatran coffee. For
56 beans at random when making a single shot, or randomly a double shot, using 14 grams of coffee, the probability of that
selecting 112 beans to make a double. The question then becomes, Sumatran coffee being present within +/- 10 percent of its
if one selects 56 beans at random out of a hopper containing this nominal composition (between 36 and 44 percent in this case)
blend, what is the chance that you get the correct number of each is contained in the fourth row. Focus on the middle portion of
bean in that sample? Intuitively, one can see that the odds improve this table, devoted to 14 grams, and look down the first column
as the sample size expands (e.g. it takes 112 beans to make a covering +/- 10 percent and read off the fourth row pertaining
double shot and it gets even better if the sample size is the 168 to 40 percent blend component, resulting in the reading of
beans required for a triple.). 66 percent. In other words, in selecting 112 beans at random,
The same is true if the blend contains a large proportion of the Sumatran bean will be present between 36 and 44 percent
a particular bean, certainly when compared to the behavior of a concentration about 66 percent of the time. In the remaining 34
coffee that is present in a much smaller proportion in the blend. percent of the time, the concentration will be outside these limits.
The table below illustrates this effect for three different doses, If the same blend had another coffee, say a Costa Rican, at
nominally a single shot, a double and a triple. The five rows a nominal proportion of 10 percent, and we require that bean
represent the proportion of a coffee in the blend (10 percent, to be present within +/- 10 percent of its nominal composition
20 percent, etc.). For example, if the blend has 20 percent of a (between 9 and 11 percent, in that case), in making the same
particular coffee, refer to the second row of this table. If it happens double shot, we find that probability to be 39 percent. It means
to be 25 percent, one has to interpolate between the results in the that in the 112-bean sample, that Costa Rican coffee will be
second and third rows. These calculations are made and rounded present at concentrations between 9 and 11 percent only 39
to the nearest whole bean. percent of the time. In the remaining 61 percent of the time, its
The columns show a measure of the “error rate” in the relative concentration will be outside those bounds.
TABLE 1. Shot to Shot Variation of Coffees in a Blend for Different Doses
Dose = 7 grams Dose = 14 grams Dose = 21 grams
Spread Spread Spread
Blend +/- +/- +/- +/- +/- +/- +/- +/- +/-
Component % 10% 20% 40% 10% 20% 40% 10% 20% 40%
10 36 52 77 39 61 88 42 68 94
20 41 64 90 48 76 97 54 84 99
30 47 74 96 57 86 100 65 92 100
40 54 82 99 66 93 100 74 97 100
50 62 89 100 75 97 100 83 99 100
Tables courtesy of Jim Schulman of the University of Chicago.
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